Patent GB-554389-A (GB)
Title: Improvements in the manufacture of refrigerating apparatus
IPC: F25B39/02
Filed: 1942-02-13
Abstract: 554,389. Welding refrigerator. ELECTROLUX, Ltd. Feb. 13, 1942, No. 1930. Convention date, Feb. 13, 1941. [Classes 83 (ii) and 83 (iv)] [Also in Group XIII] In making refrigerating apparatus, parts which are to be subjected during operation to the working pressure are electric resistance welded to the other parts not so subjected by applying the high temperature electrode to the latter parts and applying to the former parts a counter electrode arranged so that the current path extends substantially parallel to the walls of such parts. The apparatus may comprise compression refrigerating apparatus or hermetically sealed absorption refrigerating apparatus, particularly of the inert gas type. The parts of an apparatus of the last-named type may be united together in three stages consisting in first gas welding the elements of member such as the gas expeller, absorber, condenser, evaporator or heat exchanger, then resistance welding said members with other members such as heat radiating fins or supporting plates, and then gas welding the built-up members to each other or to the pipe system. A plate 15 is resistance welded to a tube 14 by applying the high temperature electrode 11 to the plate and conducting the current from the other terminal of the electric-circuit along paths parallel to the walls of the tube instead of transversely therethrough by using a large external contact electrode 13 grooved to the curvature of the tube. A portion of the centre of the electrode 13 may be drilled out to increase the welding pressure. The electrode 13 may, if desired, have a deep groove 16 and may be slotted at 18, Fig. 3, and provided with a bolt 19 and nut to clamp the tube. Also the tube may have a flattened surface 23 for engaging the plate. The parts adjacent the joints may be galvanised after welding. In welding the pump coil 20, Fig. 4, to the flue tube 21 of the refrigerator the electrode 11 co-operates with a counter electrode 13 having. a face curved to suit the diameter of the coil and provided with grooves of crosssection corresponding to the radius of the coil tube. A number of spot welds may thus be effected. The evaporator of the refrigerator may consist of two H-tubes 25, 26, Fig. 5, connected in series via a pipe connection gas welded thereto and each spot welded at a number of points by the above method to superposed plates 27, 28 which support the ice trays. The counter electrode may be a thick plate with a U-shaped groove. The plates are flanged at their front ends. The tubes and plates are located in a casing 29 of iron, aluminium, or heat insulating material welded, screwed or riveted to parts of the plates. The tubes may in another form be in the same horizontal plane, particularly for apparatus not using inert gas, and may be in an inclined plane and welded to the plate through profile bars 40, 41, 42, Fig. 9. The casing 29 may be dispensed with by using U-shape profiled plates 57, Fig. 11, fitting into each other and welded together. The plates 57 may in a modification of this form be enclosed in an outer casing 45, provided with surface increasing fins 55. Evaporater tubes 50-53 fed from a second condenser and operative only under high cooling air temperature conditions are resistance welded to the inner and outer casings. This may be effected by applying one or more grooved counter electrodes to each tube and the other electrode to the casing, or by applying an electrode with a plane contact surface to one casing and the other electrode to the other casing. Two plates may be welded on diametrically opposite lines of a tube wall by two plane electrodes applied to the respective plates. Two or more tubes may be similarly welded together along generatrices. Three tubes may be arranged in contact with each other or in a common diametral plane. In the latter case the electrodes engage the outer surfaces of the outer tubes. The condenser and absorber of the apparatus consist of tubular coils with straight portions to which are spot welded longitudinal fins 72 for guiding separate cooling air streams between individual turns of the coils. The counter electrodes in this case are provided with grooves adapted to the shape, pitch and number of turns of the coil. A number of fins may be superposed and welded in one operation to each coil and the fin edges then bent out at different angles. The Specification as open to inspection under Sect. 91 states that the counter electrode instead of engaging the outer surface of the tube may engage the inner surface away from the joint' or the current may be conducted along both surfaces. This subject-matter does not appear in the Specification as accepted.